Hello. > we have encountered CPU stalls in mainline kernel while loading the > bluetooth module. We have custom board based on rockchip rv1109 soc and > there is bluetooth chipset of relatek 8821cs. CPU is stalls while realtek > 8821cs module. > > Bug/Regression: > In current mainline, we found CPU is stalls when we load bluetooth module. > git bisect shows commit 22a9d9585812440211b0b34a6bc02ade62314be4 > as a bad, which produce CPU stalls. > > git show 22a9d9585812440211b0b34a6bc02ade62314be4 > commit 22a9d9585812440211b0b34a6bc02ade62314be4 > Author: Bumyong Lee <bumyong.lee@xxxxxxxxxxx> > Date: Tue Dec 19 14:50:26 2023 +0900 > > dmaengine: pl330: issue_pending waits until WFP state > > According to DMA-330 errata notice[1] 71930, DMAKILL > cannot clear internal signal, named pipeline_req_active. > it makes that pl330 would wait forever in WFP state > although dma already send dma request if pl330 gets > dma request before entering WFP state. > > The errata suggests that polling until entering WFP state > as workaround and then peripherals allows to issue dma request. > > [1]: https://developer.arm.com/documentation/genc008428/latest > > Signed-off-by: Bumyong Lee <bumyong.lee@xxxxxxxxxxx> > Link: > https://lore.kernel.org/r/20231219055026.118695-1-bumyong.lee@xxxxxxxxxxx > Signed-off-by: Vinod Koul <vkoul@xxxxxxxxxx> > > diff --git a/drivers/dma/pl330.c b/drivers/dma/pl330.c index > 3cf0b38387ae..c29744bfdf2c 100644 > --- a/drivers/dma/pl330.c > +++ b/drivers/dma/pl330.c > @@ -1053,6 +1053,9 @@ static bool _trigger(struct pl330_thread *thrd) > > thrd->req_running = idx; > > + if (desc->rqtype == DMA_MEM_TO_DEV || desc->rqtype == > DMA_DEV_TO_MEM) > + UNTIL(thrd, PL330_STATE_WFP); > + > return true; > } > > By reverting this commit, we have success in loading of bluetooth module. > > > Output of CPU stalls: > # modprobe hci_uart > [ 27.024749] Bluetooth: HCI UART driver ver 2.3 > [ 27.025284] Bluetooth: HCI UART protocol Three-wire (H5) registered > # [ 28.125338] dwmmc_rockchip ffc70000.mmc: Unexpected interrupt latency > [ 33.245339] dwmmc_rockchip ffc50000.mmc: Unexpected interrupt latency > [ 326.195321] rcu: INFO: rcu_sched detected stalls on CPUs/tasks: > [ 326.195880] rcu: 0-...0: (3 ticks this GP) idle=e5f4/1/0x40000000 > softirq=551/552 fqs=420 > [ 326.196621] rcu: hardirqs softirqs csw/system > [ 326.197115] rcu: number: 0 0 0 > [ 326.197612] rcu: cputime: 0 0 0 ==> > 10500(ms) > [ 326.198231] rcu: (detected by 1, t=2105 jiffies, g=-455, q=17 > ncpus=2) > [ 326.198823] Sending NMI from CPU 1 to CPUs 0: > > Expected Output: > # modprobe hci_uart > [ 30.690321] Bluetooth: HCI UART driver ver 2.3 > [ 30.690852] Bluetooth: HCI UART protocol Three-wire (H5) registered > # [ 31.453586] Bluetooth: hci0: RTL: examining hci_ver=08 hci_rev=000c > lmp_ver=08 lmp_subver=8821 > [ 31.458061] Bluetooth: hci0: RTL: rom_version status=0 version=1 > [ 31.458608] Bluetooth: hci0: RTL: loading rtl_bt/rtl8821cs_fw.bin > [ 31.465029] Bluetooth: hci0: RTL: loading rtl_bt/rtl8821cs_config.bin > [ 31.483926] Bluetooth: hci0: RTL: cfg_sz 25, total sz 36953 > [ 32.213105] Bluetooth: hci0: RTL: fw version 0x75b8f098 > [ 32.274216] Bluetooth: MGMT ver 1.22 > [ 32.285376] NET: Registered PF_ALG protocol family I discussed this issue. Could you refer to this[1]? I haven't received anymore reply from him after that. If you have any more opinion, please let me know. [1]: https://lore.kernel.org/lkml/000001da3869$ca643fa0$5f2cbee0$@samsung.com/T/ Best Regards
